Fiat's 500 city car has got bigger and is all set to grow even more as the Italian carmaker establishes it as a brand within a brand.

The 500 will be to Fiat what Mini is to BMW according to brand chief Gianluca Italia. In addition to the longer, taller, roomier 500L, currently being rolled out across Europe, further models will follow.

This will start with a 500 Trekking, a two-wheel-drive crossover type vehicle which uses Fiat's 'traction+' system which will be unveiled at the Geneva show next week. Italia said more versions will follow including a 4x4 - the 500X, "and we are looking at many other variants".

 "We are looking at a full family of vehicles. We know that the 500 is often bought by parents for their children but the loyalty to the car is low, around 60% of drivers move onto something bigger. We want to be able to offer them an extended 500 range.

 "The 500 has been a very big success and the model still has a long way to go and we have a number of new developments."

Arguably, the 500 is keeping Fiat afloat in Europe, along with the Panda, they are the best-selling small cars, taking some 35% of the so-called A segment across the region.

The 500L, said Italia, takes the 500 up one into the B segment but he expects to conquest sales from many other market areas, such as the C-segment family cars plus small and medium size SUVs.

He added: "For the first time the 500 now has five-doors, it is a full five-seater and there is plenty of room for luggage. The car might be B-segment in size but it has the interior space of a family car."

There are also two new engines for the 500L, including a more powerful version of Fiat's unique two-cylinder Twin Air turbocharged petrol unit, up from 85bhp to 105bhp while still keeping emissions down to 112 g/km.

That includes stop start and an eco mode which reduces output to 98bhp which, according to the head of powertrain Aldo Marangoni, places Fiat a full seven years ahead of the EU's 2020 emissions targets.

The second newcomer is the 1.6 litre multijet diesel with an identical 105bhp but with very different driving characteristics, said Marangoni. He added that both engines debut in the 500L but will be introduced later for other group models.